The present invention relates to a process for producing a magnetic read and write head and to a head obtained by this process. It is used in magnetic recording equipment and in particular in computer memories.
The magnetic head according to the invention is of the type comprising two pole pieces, a double flat spiral coil surrounding each of the pole pieces and an air gap filled with an amagnetic material, the latter being flush with the level of the planar surface forming what is called the flight or displacement plane of the head. The magnetic recording support moves relative to the head in front of the air gap and parallel to the displacement plane. During writing, a current flowing in the winding leads to a magnetic field at the air gap, so that information is written into the support. Conversely, magnetic information written on to the moving support induces a field in the pole pieces, i.e. a current in the coil and a voltage at the terminals thereof, which constitutes a measuring signal. As the magnetic field involved in these reading and writing operations is parallel to the recording support, the term horizontal magnetic recording is sometimes used.
For example, such a head is described in Japanese Pat. No. 56 83823 filed by FIJITSU K.K. and entitled "Production of horizontal thin film magnetic head", whose abstract was published in Patent Abstracts of Japan, vol. 5, no. 150 (P-81) (822) of 22.9.1981.
The process for producing such a head comprises the end to end bonding of two thin magnetic pieces on a substrate, said magnetic pieces being separated by a nonmagnetic layer defining the air gap. This assembly is then machined to reduce the height of the air gap. Separately a support is formed comprising a double winding surrounding the two pole pieces. These two subassemblies are then bonded together.
Such a process suffers from numerous disadvantages. Firstly, it requires sensitive fitting of small parts, which makes it relatively incompatible with industrial, automated processes. The read and write pole pieces have on the one hand a significant width, which is prejudicial to the efficiency of the head, and on the other hand is of a relatively non-reproducible nature, which leads to performance variations. Finally, it can induce interference fields in the recording layer.